The present invention pertains in general to an Ethernet transceiver, and more particularly, to an output driver for a combined 10/100/1000 BaseT Ethernet transceiver.
During the 1980""s and 1990""s, the growth and use of computer networks increased at a phenomenal rate. The mind set of decision-makers in any type of business, be it a large business or a small business, changed from deciding whether they needed networks to deciding what type of network should be employed in their particular business. This was a result, in part, of the parallel growth and the capabilities of devices connectible to the network such as personal computers, work stations, servers, etc. Additionally, the applications utilizing networks have further evolved to create some obsolescence in previous network technologies. One type of network, Ethernet, has seen an evolution from the first stage of being accepted as a viable network interconnection architecture to one wherein the speeds of the network have changed. Prior to the 1980""s, the experimental Ethernets operated at a rate of 3 Mb/s. In the early 80""s, the DIX specification was set forth for a 10 Mb/s coaxial cable Ethernet. This particular speed or data rate evolved up to the IEEE 802.3 10BASE-T standard, which resulted in use with thin wire coaxial cable and then to use with an unshielded twisted pair in the early 90""s. This further developed into the 100BASE-T twisted pair standard which allowed a much higher speed data path. In the late 1990""s, the IEEE 802.3 1000BASE-T standard was set forth which provided for a Gigabit Ethernet.
One of the problems with providing hardware for the Gigabit Ethernet is that associated with reverse compatibility. Most Ethernet controllers in the marketplace are required to handle the 10BASE-T and 1000BASE-T Ethernet standards, such that they can be used in association with compatible physical medians. This presents a problem to a designer due to the fact that the 10BASE-T operates on a different voltage level than the 1000BASE-T and the power requirements for each are distinctly different. A one volt peak differential voltage is now required for the 100 and 1000BASE-T standards and a 2.5 volt peak differential voltage is required for the 10 BASE-T device. Some technologies have utilized different hardware to provide the compatibility for the different standards. This, of course, has increased the complexity of these devices.
The present invention disclosed and claimed herein, in one aspect thereof, comprises a transmission line driver for driving a transmission line in a first operating mode and in a second operating mode. The first and second operating modes operate in a mutually exclusive manner. A current driver is provided for driving the transmission line in the first operating mode from a first data generator and at a first output voltage. A voltage driver is provided for driving the transmission line in the second operating mode from a second data generator at a second output voltage through a load, such that the current driver and the voltage driver operate independent of each other.